function [m, symbol, filterind] = model_addfilter(m, w, symmetric, blocklabel, flip)

% Add a filter to the model. Automatically allocates a new block if blocklabel is empty.

%

% m object model

% w filter weights

% symmetric 'M'irrored or 'N'one

% blocklabel block to use for the filter weights

% flip is this filter vertically flipped

% set argument defaults

if nargin < 3

symmetric = 'N';

end

if nargin < 4

blocklabel = [];

end

if nargin < 5

flip = false;

end

% M = vertical mirrored partner

% N = none (no symmetry)

if symmetric ~= 'M' && symmetric ~= 'N'

error('parameter symmetric must be either M or N');

end

% get index for new filter

j = m.numfilters + 1;

m.numfilters = j;

% get new blocklabel

if isempty(blocklabel)

width = size(w,2);

height = size(w,1);

depth = size(w,3);

[m, blocklabel] = model_addblock(m, width*height*depth);

end

m.filters(j).w = w;

m.filters(j).blocklabel = blocklabel;

m.filters(j).symmetric = symmetric;

m.filters(j).size = [size(w, 1) size(w, 2)];

m.filters(j).flip = flip;

% new symbol for terminal associated with filter f

[m, i] = model_addsymbol(m, 'T');

m.symbols(i).filter = j;

m.filters(j).symbol = i;

filterind = j;

symbol = i;